🚨(frontend) fix TypeScript errors to enable successful build

Resolved minor TypeScript errors in the Proof of Concept (PoC)
that were causing the "npm run build" command to fail.

These fixes were necessary to prepare the frontend for
containerization with Docker.

ASAP, a CI step will prevent these kind of errors.

src/frontend/src/App.tsx

@@ -12,6 +12,13 @@ export interface User {
   email: string;
 }
 
+export interface Room {
+  livekit?: {
+    token: string
+  };
+  is_public: boolean;
+}
+
 function getCSRFToken() {
   return document.cookie
     .split(';')
@@ -38,7 +45,7 @@ async function getMe() {
   return response.json() as Promise<User>;
 }
 
-function slugify(str) {
+function slugify(str: string) {
   return str
     .toLowerCase()
     .normalize('NFD')
@@ -49,7 +56,7 @@ function slugify(str) {
     .replace(/-+/g, '-')
 }
 
-async function fetchRoom(roomId) {
+async function fetchRoom(roomId: string) {
   const csrfToken = getCSRFToken();
   const response = await fetch(
     `${API_BASE_URL}rooms/${roomId}/`,
@@ -66,13 +73,13 @@ async function fetchRoom(roomId) {
     throw new Error(`Couldn't fetch room data: ${response.statusText}`);
   }
 
-  return response.json() as Promise<User>;
+  return response.json() as Promise<Room>;
 }
 
 
 function App() {
   const [authenticatedUser, setAuthenticatedUser] = useState<User | null>(null)
-  const [roomData, setRoomData] = useState(null)
+  const [roomData, setRoomData] = useState<Room | null>(null)
   const [isLoading, setIsLoading] = useState<boolean>(true)
 
   useEffect(() => {
@@ -86,7 +93,7 @@ function App() {
 
   const getRoom = async () => {
 
-    const roomName = document.getElementById('roomName')?.value || crypto.randomUUID()
+    const roomName = (document.getElementById('roomName')as HTMLInputElement)?.value || crypto.randomUUID()
     const roomData = await fetchRoom(slugify(roomName))
     setRoomData(roomData)